All of the DIY screens I read about here are the "pull black out fabric around wood frame" types. Has anyone tried to install the fabric on a roller and pull it down for use? Is it possible to do this and not have wrinkles? Will it be hard to keep it flat?

Well, I don't have experience with this, but a window shade does not have wrinkles. Paint would be out, but if you could find a fabric of the appropriate color, or find a fabric stain, this might work. I think the biggest issue would be finding a shade large enough.